Giel

This photo shows how the connection wire was wound around the ferrite core with at least 4 turns.

Here are photos of where in the inverter I found the wire that was protected by the ferrite to show the approximate location and the turns in wire.

Coulomb I found two photos on the Aussie forums at PIP inverter repairs and hardware modifications - Page 26 - AEVA Forums posted by calida82. I am adding them here with arrows pointing to the ferrite toroid named Aus Photo 2 Arrow and Aus Photo 3 arrow. I am also adding photos I took of the small piece of ferrite. I will be adding my MKS II photos in another reply. Giel

I remember the location of this 25% ferrite toroid to have been in the area "encircled" in the picture and suspect it to have been on the cable with the arrow, but my cable was much longer and once could clearly see it was turn around a ferrite toroid.

Coulomb Thank you for your reply. The batteries are indeed connected in parallel (positive to positive, negative to negative with short 50mm² battery cable). The cables to the battery disconnect fuses are the same length with the + coming from the top battery and the - from the bottom battery. My conductors are all 50mm². I have 2 x 50mm² cables from positive to my battery disconnect fuses and 2 x 50mm² cables from negative to my battery disconnect fuses. These four cables connect to 2 disconnect fuses. One positive and one negative cable to each disconnect fuse for the first 2 inverters. The battery disconnect fuse for the 3rd inverter is then fed from the battery disconnect fuses of the first two inverters with short 50mm² cables. In other words: + from fuse 1 to + of fuse 3, + of fuse 2 to + of fuse 3 and - of fuse 1 to - of fuse 3, - of fuse 2 to - of fuse 3. All these four wires are very short 50mm² cables. These are creating a DC "bus bar". When I installed the 1st two inverters, I made sure the battery cable lengths from the batteries to the battery disconnect fuses and to the two inverters are exactly the same length. In adding the 3rd inverter, I could not achieve this. The cables from battery disconnect fuse 3 to inverter 3 is about 25 cm longer than those to the two other inverters. My question and messages are long, but I must add this extra detail: The 3rd inverter is a refurbished inverter, which I bought for my son around Jul 2022. I installed one of the same Narada batteries for him. Th system was used as a UPS to help him with our South African grid loadshedding, and they had a small baby. The system had no PV panels. To cut a long story short, the inverter was not working 100%. It seemed to struggle to take the load when the grid went off. I took the unit back to the supplier and it was checked and cleared of any flaws. My son moved 5 months later, and I recovered all equipment, used the battery at my house and boxed the inverter and all switches. I unboxed the inverter now and when I picked it up, I could hear something falling around inside. I had no choice than to open it, my first time opening one of these. I checked all the available service manuals I could find. I found a very small piece of ferrite toroid inside. I could not locate the other bigger part of it. It was about a 25% piece of a full ferrite toroid core/ring with outer diameter of about 35.5mm, inner diameter of about 23mm, width of about 12.7mm and thickness of about 6.2mm. I could get the outer and inner diameters by taking this small piece and drawing a circle on a piece of paper, measuring it with a vernier and then comparing against what is available in the industry. Having looked carefully, I could see where this came from. It was used on one cable between two boards and must be some sort of noise suppression. I cannot tell you now between which boards it was as I did not check it. It came from a longish cable to the left of the left heatsink below the MPPT and under a small board mounted to the left bottom of the MPPT. I tried to locate this ferrite core/ring on pictures posted on this forum and the Australian forums and in service manuals but could not find any and decided to close up the unit and test it. The unit switched on and I could change all settings to match my other two inverters. Having changed the settings, I shut it down and completed all the outstanding wiring and also did the revised parallel connections. On starting up all three inverters, this 3rd inverter did not want to switch on at all. I had to restore the parallel wiring to two inverters and then opened this 3rd inverter. I found that the main battery positive fuse was not properly secured. I removed it and could clearly see traces of arcing between the fuse and the top connection on the PC board. I am attaching a photo of the fuse before cleaning it. I cleaned the fuse and sprayed it with electro cleaner, spray electro cleaner on the contact on the PC Board, put the fuse back and secured it properly and walla, the inverter switched on. This must have been the fault we detected way back in Jul 2022. I restored all the parallel wiring, started everything up and load tested the capacity and since then all is fine. This is about two weeks ago. I am wondering whether this ferrite toroid or the fuse or both might be contributing to my switching issue. I am suspecting the fuse as it does not seem to be the original fuse, has no identification on it and I could not find out the specifications in any user or service manual and our local Mustek supplier plus two inverter repair shops would not tell me. I suspect this is a 200A 58V mega fuse. Its overall length is about 35mm and the distance between the center of the two mounting holes is about 25mm. I am feeling that this fuse must be replaced as it could cause a voltage drop based on the arcing surface I had to clean, so I will appreciate confirmation of the specifications of the fuse. Below is a picture of which fuse I think it must be and I am attaching its datadsheet for confirmation. Once I find a replacement fuse and have to open it, then I can determine exactly which cable this ferrite toroid was fitted on, between which boards this cable is connected and I can take pictures as well. That way you might be able to confirm whether this ferrite is important to replace. I noticed that one gets lots of ferrite toroid's with the same dimensions, but all having different electrical specifications. In the case that this one cannot be properly identified, I can then open one of the other inverters to check whether it has a similar one, take a picture of where it is fitted and take some measurements. I hope this message is clearer than mud and that you will be able to assist. Thanks Littelfuse-Datasheet-153-BF1-58V-r4-0.pdf

I had 2 of these inverters installed in Dec 2019 with 2 strings of 7 x 325W PV panels. I added PV panels along the way and upgraded my system now in Jan 2025 to be as follows: 3 x MKS II in parallel, Inverter 1 (Master) with 7 x 325W panels facing north, Inverter 3 with 7 x 325W panels facing north and inverter 2 string 1 with 7 x 330W panels facing north and string 2 with 7 x 330W panels facing west. I have 6 x Narada 48NPFC100 batteries. I use a Raspberry pi for monitoring with the latest ICM software version (looks like 1.25). Total inverter peak capacity = 15kW, total PV capacity 9.17kW and total battery capacity = 4.8x6=28.8kWH (23 kWH usable to 20% depth of discharge) I did this upgrade from 2 to 3 inverters to make provision for peak usage exceeding 10kW (which happened occasionally) and to make provision to install inverter-based air conditioners in the near future. I tested the capacity of the upgraded setup to about 14.6kW from the battery and solar with the AC grid disconnected. Before I did this upgrade, I used to run my setup in off-grid mode as I switched the AC Grid off. I could manually switch the AC grid on if I was at home or remotely switch it on using a Sonoff device connected a suitable contactor. This worked fine, but I had to monitor the batteries to make sure it does not discharge too much when we were away from home, say on weekends or on holiday. With the upgraded setup, I wanted to automate this to allow the inverters to make that decision to allow me not to have to monitor the system regularly. Iset the following settings: 1. In the "Control Settings" menu under "Settings", selected "Time For Different Modes" to be ON, selected "SOC for Control" to be on and ticked SBU in all cells in the table. 2. The inverter settings are: "Charger source priority" = Utility and Solar, "Output source priority" = SBU, "AC input range" = UPS, "Battery type" = User, "Back to grid Voltage" = 46.0, Back to discharge voltage" = 48.0 I switched the AC grid on and tested the upgraded setup. I then noticed that the system would occasionally switch from battery to grid during the day while the battery is almost fully charged and with the sun shining. I investigated and noticed that this seems to happen with high loads (more than 10kW) and when a cloud obscures the sun. After about 10 minutes or so, the system will switch back to battery. Then there was a case where the load was about 13kW and no switching happened. On another day when the load was again above the 10kW mark, the systems switch to grid again. I first thought it was the settings related to Back to grid Voltage and Back to discharge voltage. These were higher, but I changed them on all inverters to the voltage above. I also studied the Narada battery specifications and noticed that their disconnect voltage is about 40.5V for older batteries. This seems to be higher for the newer Narada batteries. I then monitored the battery voltage while increasing the load to see whether the voltage drops to cause a switch to grid. The battery voltage drops under high loads, but never got close to 46V, in fact, it was above 48V. Based on my findings, I am considering going back to my old ways of just switching the grid off. Our average grid usage is about 0.7 kWh per day since Dec 2019. Does anyone have an explanation why this is happening (switching from battery to grid) and what I could do to rectify it?

Monday, if the weather permits, the number of PV panels will be increased to almpst double the PV capacity. I suspect that we will notice a significant improvement in yield from the current 4 east facing panels as this will be increased to 6. Then as mentioned above, another west facing string with 8 pnaels will be added. From Tuesday we will monitor this 500W power decreasing phenomenon again. If it still happens, we will do a number of things to find the cause namely: 1. A new confirmed legit, reputable installer is now contracted and will do the PV instalaltion on Monday. Maybe he can help Monday already, depending on the time of day they complete the installation. It could potentially be wiring or a setting. 2. If this persists and the cause is not identified, then I will go to a friend here in Pretoria and take screen shots of all the settings menus to compare. 3. If that does not identify the cause, then the position of the CT coil might be the cause. I suspect it is currently installed on the incoming mains in the DB box in the garage, next to the two 5kW inverters. If so, then maybe the metal box or inverters itself (EMI) or something might be interfering with the inductance of the coil and cause incorrect measurements. This is far fetched, but not impossible. I noticed with my installation (Mecer Axpert inverters) that the EMI from the inverters had an influence on the remote receiver of my alarm system. I had to move the remote receiver away from the inverters. If this is the case, then we will have to accept it as we might not find an alternative position to install it.

I did untick the grid charge from 9h00 to 17h00, but had to put it back today as the sun was not that great in Cape Town area and there was more load due to house cleaning activities, doing washing, tumble drier, ironing, etc. Will try again once extra panels are installed.

I am in Pretoria and my son in Somerset West. I hope the additional panels will be installed within a week or so. Then we will see if the response regarding the 500W is the same or not.

Hi Talia I am not sure from which inverter MPPT the drop is coming from. I could have checked it, but cannot remember. You are 100% correct about the 4 panels being close to the inverter startup voltage of 150V. We are busy addressing this and this should be sorted soon. These 4 panels are east facing and we can add two as that is the space available on that roof. We will also add 8 more panels on the west facing roof on MPPT2 of the master. This will then be the maximum solar capacity the roof space can handle. The total solar will then be as follows: Master MPPT 1: now 4 panels x 425W (1700W) to increase to 6 panels x 425W (2550W) Master MPPT 2: now 0W to increase with 8 panels x 425W (3400W) Slave MPPT 1: now 8 panels x 425W (3400W) and will stay like so. Total now 12 panels x 425W (5100W) to increase to 22 panels x 425W (9350W). This is potentially an overkill, but only the slave 8 panels are north facing. The master MPPT 1 panels are east facing and the master MPPT 2 panels will be west facing. So the capacity is kind of the slave MPPT 1 panels (3400W) plus either the master MPPT 1 panels or the master MPPT 2 panels or something inbetween. Giel

Hi Scorp007 We are using grid time settings as shared with Tim. I cannot remember wat the SOC was when the grid came on. Giel

Hi Tim. Here are the current time settings Giel

My son had 2 x Deye 5kW inverters installed in parallel with 2 x Deye 5.32 kWh batteries. The slave has 8 x 425W panels (3400 W) on one string and the master has 4 x 425W panels (1700W). We will be adding busy to get this 1700W changed as the voltage is a bit low. We will be adding 2 more 425W panels as this is what the roof space allows. This was installed in a new built house and the grid was not conencted yet. My son moved in a few days ago and could track the production. Yesterday the grid was connected. The moment the grid came on, the total PV went down by about 500W. This morning I noticed that the PV power curve is starting later than yesterday. I montired it and then asked my son to switch off the incoming grid mains switch. Immediately the production increased by about 500W. Is this normal? If not, why is this happening and what needs to be changend?

Any other simple/easy ideas to load test the panels in order to determine their yield?

Coulomb, why is it dangerous? I have done this test with a 3kW geyser element judt yo see if the element will hear up and had no issues?

@razzor13bt, if I remember correctly, you have 4 strings of 2 x 480W panels. The Vmp per panel is 41.4V as per your post on 29 June. If that is correct, then you should be getting around 80V DC between PV+ and PV- per PV string. Your Imp current per string should be about 11.6A as per the specification. The total power per string is 960W and the total PV power for the 4 strings should be 3840W. My estimate is that you should be getting between 70 to 80% of this or up to 3100W. If you multiply this by an average of 5.5 sun hours per day for Gauteng, then you be producing around 17 kWh (units) per day. If "Gnd" above means "PV-", then if you measured between PV+ and earth (at the bottom right of your orange surge arrestor in your PV combiner box as posted by you on 17 June) and again PV- (Gnd) and earth on your PV combiner box, with the panels connected, the total voltage per string seems a bit low. For instance St 1 = 22 + 14 =36V, St 2 = 21.6 +14.3 = 35.9V, St 3 = 22 +14 = 36V and St 4 = 22 + 14.1 = 36.1V. Is this correct? If it is correct, I think this is below the operating range of the King, which is 60 to 115V DC. Previously you stated that you measure around 64V using 2 x 500W panels from a friend of yours. Even that 64V is close to the lower limit of the King. This means that either the panels are under performing or you have a wiring issue on each string. I prefer to use 6mm2 solar wire between the panels and the PV combiner to reduce losses, but using 4mm2 should be fine. The MC-4 connectors should be properly secured/mated. You can feel the connectors and the wiring to find any hot spots. If it is warm, you should investigate. I would remove four panels from two strings and test them on the ground or if you can, connect them together on the roof, but first disconenct it from the inverters. Put these foure panels in series. It will be 1920W and should produce around 160V when conencted. be careful not to touch the wires as this can be a shocking experience. You can connect a 2kW geyser element as a load. Measure the current using a clamp on amp meter while mesuring the voltage at the same time. Mulitply the current and voltage to determine the watts. Just be careful, do this quick as that element will get very hot. If you do not get close to 1920W, then try to change the angle of the panels and make sure they face to the sun to try to increase the power. This way you can confirm whether the panels are actually producing what they should or whether they are below par.

I disconnected the solar string from the inverter with the DC isolator in the PV combiner box. I then measured 3V DC between PV+ and earth and 8V between PV- and earth.

@Jaxone why would this be a big problem? I need some explanation to understand why I should change it. The wiring was done according tot South African wiring standards in order to get what we call here an electrical Certificate of Compliance (COC).

My one inverter has 2 strings of 7 x 325W panels and the other inverter 1 string of 7 x 330W panels. I measure about +40V between the string + and earth and -184V between the string - and earth. Is this a problem? Here by us in South Africa we have to connect the panels with an earth wire to each other on the earhing point of the PV panel frame. I used 6mm2 between the panel. Then we have to connect that earth from each PV string to the AC electrical earth of the house in the AC distribution box. I used 10mm2 to connect the strings together and to the AC earth. The inverters are also earthed to the same AC earth. The earths of the batteries in the battery cabinet are also connected together and also connected to the same AC earth. The inverters and the batteries are connected together with a 10mm2 cable to the AC earth. For lightning protection, I earthed the solar panels via a 16mm2 cable to an earth spike as well. I actually have to earth spikes, connected together with bare copper wire, all under ground, to increase the area of the earth. In addition, I have DC surge protectors in each of my two DC combiner boxes.

Hi Calvin (and all other on this thread) I am in Pretoria and have two Axpert (Mecer branded) MKS II inverters in parallel and also noticed a similar "under" performance. Initially (December 2019) I had two strings of 7 x 325W panels and the yield seemed to be close to 100%. I upgraded to three strings of 6 (with 1 string having mixed panels) during October 2020 and the efficiency was around 91%. I recently (23 July 2023) upgraded to 7 panels per string. For a week or so during July 2022 I got the upgraded watts, but now the strings are down to about 80% efficiency, which seems to be "industry standard" as a result of losses due to angles, heat and wires. My specs and setup are as follows: Inverters MPPT: PV Array max power - 4500W, Min PV voltage - 120VDC, PV VOC - 450VDC, Max input current - 18A and I have seen somewhere in the manual that the Max operating voltage is 430VDC. Inverter 1 PV String 1: 7 x 325W, Vmp - 38.33V, VOC - 45.80V, ISC - 9.03A, Imp - 8.48A, Total = 2275W, Voc total - 320.6V, Vmp total - 268.31V, Inverter 1 PV String 1: 7 x 325W, Vmp - 38.33V, VOC - 45.80V, ISC - 9.03A, Imp - 8.48A, Total = 2275W, Voc total - 320.6V, Vmp total - 268.31V, These two strings have a total power of 4550W and a total Imp of 16.96A. I know the power is slight above the inverter specs, but with losses it should be fine. Inverter 2 PV String 1: 7 x 330W, Vmp - 37.5V, VOC - 46.80V, ISC - 8.80A, Imp - 9.16A, Total = 2310W, Voc total - 327.6V, Vmp total - 262.5V, I currently have 4 x Narada 100AH or 4.8kW batteries in parallel. The batteries are specked to charge at 0.2C or then 20A. So the total charging current I require is 4 x 20A = 80A. I set inverter 1 to charge at 50A and inverter 2 to 30A. I am using ICM (similar to ICC and written by the same people) with a Raspberry pi 3. I changed from ICC to ICM as ICM supports the Narada BMS. In addition, ICM requires a cable to each inverter from the pi, thereby reading the value directly from both inverters. I understand that ICC reads values only from the inverter where the cable is connected tot he pi and estimates/calculates the 2nd, 3rd ... inverter values. I bought a clip on meter to be able to measure both AC and DC current. I can say that by measuring the volts and amps of my strings, I confirmed that the values reported by ICM are correct. I can see that inverter one sometimes gets close to 80 degrees Celcius and inverter two is 10 to 15 degrees lower. I am 98% disconnected from the grid as 98% of our electricity requirements are produced by these two inverters according to ICM. I disconnect the grid with a 60A trip switch. This is my normal state. I can connect the grid remotely using Sonoff and a contactor or by using the trip switch when I am at home. I am going to automate this in the near future. . I have three options namely: 1. Reverse the fans. Calvin did you physically just turn them around or is there somewhere on this forum instructions how to do this to allow the inverters to run slightly colder? 2. I can run a test by disconnecting or bypassing one panel in Inverter2 PV string to make it 6 panels to see whether the efficiency improves. If it does, then I can do the same with the two strings of inverter 1. Then I will consider to make a 2 mixed strings for inverter 2 having 1 x 325W and 5 x 330W panels each. I just do not have time right now to experiment as I have a few other tasks on my hands. 3. The 3rd option is to wait until middle December 2022. I helped someone to build a "UPS" consisting of the same inverter and battery than my setup. I intentionally bought the same equipment, in case I had to take it back. This became a reality as the person will be moving to Cape Town. So I will upgrade my current setup to 3 inverters and 5 batteries in parallel after 15 December 2022. I can then connect 1 string of 7 panels per inverter to balance them all. I will then set all inverters to charge the batteries at 30A or a total of 90A, which is 0.18C. Maybe I will get a slightly longer life from the batteries. This sounds very good as it will reduce the workload of inverter 1. However, I am still concerned that it might not necessarily increase the yield. I say this as inverter 2 currently does not get close to the PV power. It might if I reverse the fans. I will appreciate opinions. Thanks

I designed my solar system and had the following installed: 2 x Axpert MKS II 5K in parallel, 14 x 330W Canadian solar panels in 2 strings of 7 and 3 x Narada 48NPFC100. This system allows me to switch the grid off as long as the sun shines and a bit longer. Initially the installer installed the 2 strings of panels to one inverter, but I split it to have 7 panels per inverter. The system was installed early in December 2019. Everything still works fine. We are in Pretoria and generally we have more power than what we can use. On cloudy days we do survive, but when the clouds are very low, the yield is low. I kind of figured my batteries charge to around 70% to 80% or sometimes a bit less on heavy cloudy days. I do understand this, but I am considering to add a few panels for such days. The inverter spec is max 4500W, max VoC is 450V, and the MPPT range is 120V to 430V. The panel spec is 330W at Vmp of 37.2V with a VoC of 45.6V. There are a number of options to increase solar capacity as follows: 1. Add up to a maximum of 2 more panels for each string to increase it to 8 or 9. The power for 9 panels will be 2970W per inverter, 410.4 Voc and Vmp of 334.8. 2. Splitting the system into 3 strings of 6 panels with one inverter having two strings and the other 1 string. The power to one inverter will be 3960W and to the other 1980W with the Vmp = 223.2V and the Voc = 273.6V. 3. Another option is to have 4 strings of 5 panels, 2 per inverter. So each inverter will have 3300W in total and the per string Vmp = 186V and Voc = 228V. Each option has pros and cons. Option 1 is easy, but will need to split it anyway if I need to upgrade beyond 5940W solar. Also, to use rule of thumb safety, the Voc x 1.1 is close to the inverter Voc max for those cold winter days. The advantage of option 1 is that the MPPT minimum voltage will be met earlier in the morning and last later in the afternoon, getting perhaps a slightly longer number of hours out of it. Option 2 is somewhere in the middle, is unbalanced, but allows for easy future expansion. A disadvantage is that one inverter will carry a higher load in terms of battery charging and might reduce its longevity. Option 3 is a balanced system, but the Vmp is to the lower end of the MPPT range. So it will start charging later in the morning and stop charging earlier in the afternoon. The middle of the MPPT range is at 275V. My current installation is 260.4V and sometimes shows 270V or more. With Option 1 the calculated MPPT voltage is 334.8V, with option 2 it is 223.2V and with option 3 it is 186V as mentioned above. A) Does anyone have experience on the “sweet spot” for this inverter in terms of MPPT range and does it matter where in the MPPT range the inverter solar input is? Is it a problem to have an unbalanced system where one inverter has to charge the battery more than the other? In other words, is option 2 ok? C) Any expansion just for the sake of cloudy days is not really worth it in terms of return on investment, but at least I will be more independent of any potential grid power failures on such days? When the system was installed in December, we had lots of rain and cloudy days and also load shedding. So those days I will be better off. Any comments? D) Which of the above or other options will you recommend? E) Any other views and suggestions are welcome.